They approved your new card when you had "x" number of cards with "$y" available credit. They felt "$y" was within your means so approved your request. Immediately (well...almost) they learn you now have "x+" number of cards with "$y+$$$" total credit available and are now not so comfortable with you.

In days past, the fact that you paid over min-due and on time was all it took. The newer increased credit lines were irrelevant. In today's economy, they're looking more at your available credit. While you may have excellent credit history ... if you were to lose your job today you may need to run-up all that available credit ... and you now have no income. No CC company wants to be the one left standing with that bad debt. So yes. now-a-daze they can and will close your account if your available credit jumps (you did it for mileage bonus, many more folks do it cuz they know they'll soon file for bankruptcy).

As for the 40K bonus miles ... I agree with others that I don't think Barclay's can touch this ... assuming US has posted them.